Systems for delivering fuel from a storage tank to a receiving tank typically include a pump for pumping the fuel from the storage tank, through a feed line and meter, to a nozzle for delivery to a receiving tank such as the fuel tank of a vehicle, for example. The meter measures an amount of fuel delivered to the receiving tank for permitting calculation of the cost of the fuel delivered to the receiving tank. If the fuel being so pumped includes a high percentage of air, the typical fuel meter will measure both the amount of fuel and air passing through the meter to the nozzle, causing a customer to be overcharged for the amount of fuel he receives by a factor equivalent to the percentage of air in the fuel passed through the meter. As a result, most industrialized countries set strict standards for the air/fuel ratio permitted for fuel being pumped through a meter for permitting calculation of the price to be charged to a fuel user. For example, typical European weights and measures standards require that the total error caused by air in measuring the amount of fuel being distributed from a pumping system cannot exceed 1.0 percent for diesel fuel, and 0.5 percent for gasoline, when tested with air entries from 0 to 100 percent in the pumping system. It is believed that Australian requirements are the most stringent, setting a standard maximum error of 0.5 percent due to air in measuring the amount of any fuel being pumped or delivered to a user.
One known fuel pumping or distribution system includes a passive type air separation system. In this system, discussed in greater detail below, the fuel/air mixture is delivered from a pump to an air separator housing, in which air floats to the top of the housing via the bouyant force acting on bubbles formed in the fuel in the housing, whereby the air is exited through a vent tube to a sump system. The internal pressure in the sump is at atmospheric pressure, whereas the pressure in the air separator is at a pump discharge pressure (ranges from 20 to 40 psi). The air, being less dense than the fuel, flows towards the zone of lowest pressure. Passive systems are effective for fuel pumping or delivery systems having air flow rates of less than 5 percent of total flow rate. However, such passive systems cannot handle air flow rates of 100 percent air mandated by a weights and measures requirements of many countries.
The present inventor recognized that a passive type system for separating air from fuel is not capable of removing sufficient air from the fuel to meet modern standards. Accordingly, he developed the pumping system of the present invention including a dynamic system for separating air from the fuel.